drivers: hierarchize drivers Kconfig menu

The menuconfig for drivers are getting more and more cluttered
and unreadable because too many entries are displayed in a single
flat menu.  Use hierarchic menu for each category.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
[trini: Update to apply again in a few places, drop USB hunk]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/led/Kconfig b/drivers/led/Kconfig
index de5feea..b21bc94 100644
--- a/drivers/led/Kconfig
+++ b/drivers/led/Kconfig
@@ -1,3 +1,5 @@
+menu "LED Support"
+
 config LED
 	bool "Enable LED support"
 	depends on DM
@@ -24,3 +26,5 @@
 	  GPIOs may be on the SoC or some other device which provides GPIOs.
 	  The GPIO driver must used driver model. LEDs are configured using
 	  the device tree.
+
+endmenu